Questions tagged [odds-ratio]
A measure of association between two binary variables equal to the odds of a 'positive' outcome in 1 variable divided by the odds in the other. The OR ranges (0, infinity). It has a strong connection to logistic regression.
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Group level effects (odds ratio) - dummy coding vs. effect
I ran a logistic model in R's brms, with a categorical variable (condition) with two levels as predictor. When interpreting the ...
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1answer
22 views
Log odds Standard Error
I am reading a paper on how the authors calculate the variance/standard deviation of what appears to be log(odds).
The paper is a medical paper (Discontinuation of Oral Antivirals in Chronic ...
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Correct interpretation of odds ratio
I am wondering what the correct way of interpreting an odds ratio is. For example, suppose we have that the probability of success is $p=0.8$. Then, the odds ratio is:
$$
\frac{p}{1-p} = \frac{0.8}{0....
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Odd Ratios Change After Including Other Independent Variables… What does that exactly mean?
I am currently writing my master's thesis and I want to identify whether Austrians living in Vienna are more likely than immigrants in Vienna to become self-employed. In order to find out whether this ...
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How to interpret multinomial regression results? [duplicate]
I want to investigate the relationship between stock traders' past success rate (i.e. the number of total winning trades divided by the total trades executed) on the status of their current trading ...
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1answer
19 views
When to exponentiate: the mean of the chain or at every step in the chain?
I am interested in when it is best to exponentiate a difference in log-odds
Here is a sample problem in the stan language, three groups of forty binary observations, group 1 with hit probability = 0....
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54 views
Interpreting odd's ratios
If A is a binary faction (1 A and 0 not A) and if the odds ratios of A to B is (say) 1.2409 (24 percent or e ^ 0.2158). Then is the odds ratio of B to A 76% or 1 – 0.24?
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Odds ratio confidence intervals and p-values suggest different conclusions in a binary logistic mixed-effects model (glmer)
I am running a generalized linear mixed-effects model in R using the glmer function of lme4. The outcome variable is trial-level accuracy in a task (incorrect trials are 0, correct trials are 1), and ...
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Effect size in linear mixed models
Thank you for reading this question.
I know there have been a few discussions regarding this topic, but I couldn't get a satisfactory answer. So here is my question, with some details in the ...
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1answer
48 views
Baffled by inconsistency between 95% CI for OR and p-value
I am using logistic regression to model the effect of two production variables on the occurrence of tuberculosis. My independent variables are A (farm size: 0 for small, 1 for large) and B (cattle co-...
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Ratio as independent variable for logistic regression
I am trying to model the association between "previous 2 year history of no shows for consult (independent variable)" with current no shows (dependent variable) using a logistic regression model.
The ...
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1answer
35 views
Convert odds ratio back to logit - logistic regression
I'm attempting to convert odd's ratios reported in results back to their original logit form. From what I've gathered, the appropriate formula to do so is:
...
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Does the “divide by 4 rule” give the upper bound marginal effect?
In the logisitic regression chapter of "Data Analysis Using Regression and
Multilevel/Hierarchical Models" by Gelman and Hill, The "Divide by 4" rule is presented to approximate average marginal ...
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Relative Risk Constraint?
I am starting to dig into some epidemiology and am just starting to get into the nuances of relative risk (RR) vs. the odds ratio (OR). In the Fundamentals of Biostatistics, I read:
"Although ...
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1answer
46 views
Interpreting infinite odds ratio and confidence interval from Fisher's test
I've performed a two-sided Fisher's exact test on the following data, and the results include Infinity for the upper confidence interval and odds ratio. Are these results erroneous, and if not how do ...
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Interpretation of chisquare and odds ratio
I am studying te association between variables and used the chisquare test and the odds ratio of fisher exact test. I would like to know the exactly interpretation that i can do.
The main variable is ...
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Multiple risk ratio analysis or single multiple logistic regression for survey
I was asked by a doctoral student to analyze the answers to an old questionnaire her lab has and would like to publish the results of.
There are a few questions with regards to animal care and disease ...
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1answer
18 views
Comparing odds ratios of the same predictors and the same outcome across category of gender
I have two logistic models assessing the correlates of a binary outcome in males and females, respectively. The predictors are the same in both groups.
I want to see if the effects of the predictors ...
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Meta-analysis for case-control studies, confounding factors
Is there a way to adjust the pooled summary effect size (odds ratio) for confounding factors while performing a meta-analysis in R studio?
I am performing a meta-analysis and I don't want to pool ...
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29 views
What test to use to compare two proportions (and calculate effect size and confidence interval)?
There are many related questions here and elsewhere, but I found no satisfying answer.
There are plenty of related tests and concepts: Z-test, chi-squared test, G-test, McNemar's test, Fisher's exact,...
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Regarding interpretation of Odds Ratio
I have just read in my professor's lecture notes that the Odds ratio $\psi(x)$ takes non-negative values, and that the the effect of $X$ (the predictor) on $Y$ (the binary target variable) is measured ...
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Probability of association in logistic regression models
I’m using a logit model to evaluate the association of a set of habitats (H) to a particular land cover. Both land cover and H are binary variables.
...
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1answer
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How does fisher.test calculate the confidence interval for the odds ratio in R?
The fisher.test function in base R by default returns a confidence interval for the odds ratio in a 2x2 contingency table. For example:
...
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1answer
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Strange odds ratio (OR) derived from Fisher's test
I have frequency data for about 1000 genetic marker for two groups that I want to compare them between the two groups. I used Fisher’s test (in R) on the count data and got FDR and odds ratio (OR) for ...
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Creating a Weighted Ratio Based On Size of Customer
I am attempting to created a weighted ratio/score for customers based on the number of support tickets they have entered in a time period against the number of units they have in service with us.
...
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1D Bayesian Inference clarification
I'd like some help making sure I understand a 1D Bayesian inference problem.
Say I have a data vector which is an array of the number of flu cases reported weekly in California for the past 10 years.
...
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predict important markov chains(paths to an event) with confidence
I need help in validating my current approach as well as find any alternative approaches I could use in order to tackle issues like below.
I have a dataset like below and I need to find important ...
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1answer
59 views
Odds ratio not between the two odds ratio of a stratified analysis
This is not the first time I have performed stratified analyses based on logistic regressions, but I have never before been confronted with this situation.
When I test my relationship in the overall ...
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48 views
Odds Ratio, More Likely vs. As Likely, do I need to subtract 1?
When reporting odds ratios from a logistic regression, I've seen the words "as likely" and "more likely." If the odds ratio is say 3.5, I know that I can say females are 3.5 times as likely as males ...
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18 views
How to compare odds ratios across stratified sub-groups
From a randomized controlled trial, I have odds ratios (ORs) of disease A for an intervention vs control group.
I want to see if the OR differs according to deprivation.
I plan to stratify my study ...
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Interpretation of two odds ratios derived from two different cohen's ds, comparability for meta-analysis?
I have a question regarding the conversion of cohen's d into odds ratio (OR) and the comparability of results from two different situations. I wonder if the ORs derived from the two situations can ...
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reversal of odds ratios in covariate adjusted model
I am using a survey weighted GLM in R for a binary outcome. The raw risk ratio and the unadjusted ORs suggest that group 2 has significantly lower risk/odds. In the covariate adjusted model, the ...
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1answer
24 views
Converting OR to probabilities
I'm trying to understand some of my data in a logistic regression. I plotted headache (yes/no) vs. age and get an OR of 0.95.
Now I realize this means that for every year 'younger', you have a 0.95 ...
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Conclusion for not rejecting a null hypothesis
I'm actually quite confused what is the outcome we could deduce here for the other exercise types listed in the diagram.
From my interpretation, the null-hypothesis is: There is no association ...
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1answer
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How does non-response bias affect the Confidence Interval
I asked earlier what is the idea behind putting up Table 3.
I have a follow up question on how non-response bias identified can justify the different sizes of Confidence Interval(CI) in Figure 3. My ...
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1answer
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The effect of a lack of dose-response results on odds ratio
This is part of a quantitative reasoning assignment I was working on.
The study hypothesized that exercise may reduce the risk of disability for activities of daily living(ADL). However after ...
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1answer
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Deriving the values of the range around the mean value
This is part of a bigger quantitative reasoning assignment I was working on.
My understanding here is that the upper bound and lower bound of the ranges for each of the exercises should be reflected ...
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How do I interpret the odds ratio of an interaction term in Conditional Logistic Regression?
I am wondering what the correct interpretation of the odds ratio of an interaction term in conditional logistic regression is.
Let's say there are two independent variables A and B, as well as an ...
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ODDS RATIO, NNT CONFUSION
I'm really confused.
I have 3 drugs and the following odds ratios were retrieved -
A 1.71 (95% CI=1.25-2.33)
B 1.58 (95% CI=1.12-2.22)
C 1.48 (95% CI=1.12-1.95)
These values were generated with ...
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Comparing adjusted odds ratios in a model
I have a pretty basic question. Say I run a logistic regression model with 2 variables both dichotomous. falls= sex+stroke+depression. I get 3 different odds ratios, one for males vs females, one for ...
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1answer
27 views
How to interpret OR confidence intervals for interaction or confounding?
This is a textbook problem I've been trying to understand I wanted to check if my thinking is correct (unfortunately there is no solution manual) I have a case-control study where I'm looking at ...
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1answer
28 views
COMPARISONS OF ODDS RATIOS
For example, if I have 3 different trials each for 3 different drugs and I used meta analysis (sub group analysis) to generate effect sizes. How can I interpret the effect sizes? All drugs are being ...
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Do small odds ratios observed at multiple time points equate to a large odds ratio when averaged across time points?
I am testing the relative odds of two groups, placebo vs active treatment, guessing that they received active treatment. These guesses were made at four time points, 4, 8, 12, and 24 weeks into a ...
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277 views
How to manually calculate odds ratio for continuous variables?
In school, long before learning about logistic models, I've been taught how to calculate odds ratios by hand.
Formula was based on a contingency table, just like this:
This is very easy to ...
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1answer
52 views
Re-calibrating Intercept on logistic regression models for unbalance data
I have data-set that I’m modelling using logistic regression as land.cover~H1+H2+H3+H4+H6+H8+H14. My response and categorical variables are binary. However the number of 0 and 1 in my response ...
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Why is information gain rarely used as a reported effect size?
Commonly, in reporting effect sizes in medical articles, papers typically report: risk difference (RD), relative risk (RR) and odds ratio (OR) (and for variable timescale cases and other situations, ...
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How to compute (and report correctly) the signifiance of interaction effect on categorical data, using logistic regression
I want to study the odds of success and failure at some test, depending on gender and some other categorical variables. I calculated the Odds Ratios (OR) of success using Logistic Regression, with « ...
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1answer
53 views
Odds Ratio Vs. Risk Ratio
Relative risk, odds ratio, risk ratio, risk difference - these are all measures of the direction and the strength of the association between two categorical variables.
Can I use any of these four ...
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1answer
174 views
Connection between Hazard Ratios, Survival, and Probability
According to this wiki link, the hazard ratio relates to survival according to the following equation
$$
S_1(t)=S_0(t)^r \quad (1)
$$
where $S$ is the survival and $r$ is the hazard ratio. So from ...
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Using log odds ratio to compare bigram frequency between 2 profiles
I was reading an article where the author proposed using the log odds ratio calculation to compare the relative frequency of bigrams between 2 websites. From my understanding the odds ratios are used ...
